Puff topography measurement plays an important role in elucidating the factors that maintain regular tobacco use. Generally, topography is assessed in laboratory settings via mouthpiece-based, desktop devices. Recently, a portable mouthpiece-based device became available for use in naturalistic settings. However, smoking behavior in any setting may be influenced by measurement equipment (i.e., the mouthpiece). Understanding the extent to which mouthpiece-based measurement equipment alters behavior is critical, and will require comparison of laboratory-based and portable devices with nonmouthpiece-based measurement. This proposal describes two studies. The first compares mouthpiece-based desktop and portable topography measurement with video recordings of participants' smoking in a laboratory. The second compares the more naturalistic mouthpiece-based device from study 1 with video recordings in a non-laboratory environment. Both studies use 30 smokers and within-subject designs to investigate whether a mouthpiece influences a variety of puff topography variables, including puff number, duration, and interpuff interval. Results from this project will help maximize the validity of future studies that rely on puff topography assessment. Conducting this research will provide valuable experience related to the responsible conduct of research with human participants, as well as issues related to data collection, analysis, and reporting across diverse research sites. These experiences will help me achieve my goal to become an independent drug abuse researcher.